Highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefins such as norbornene (N) or of their coPolymerization with ethene (E) or propene (P). The polymers obtained show exciting structures and properties. E-N copolymers are industrially produced materials, with variable and high glass transitions depending on the wide range of their microstructures. By realizing the possibility in great variety of stereoregularity of propene and norbornene units and the difference in comonomer distribution, P-N copolymers were expected to have fine tuned microstructures and properties. Moreover, P-N copolymers should be characterized by higher Tg-values than E-N copolymers with the same norbornene content and molar mass. A review of the state of the art of P-N coPolymerization by ansa -metallocenes of C2 symmetry, namely rac -Et (Ind) 2ZrCl2 (I-I) and rac -Me2Si (Ind) 2ZrCl2 (I-II), and rac -Me2Si (2-Me-Ind) 2ZrCl2 (I-III), and of catalysts of Cs symmetry, namely (tBuNSiMe2Flu) TiMe2 (IV-I) and derivatives, is given here. Special emphasis is given to microstructural studies of P-N copolymers, including stereo- and regioregularity of propene units as well as of comonomer distribution, stereoregularity of norbornene units, and the structure of chain end-groups. This information allows us to find a rationale for the catalytic activities and the copolymer properties.

Gas phase Polymerization of propylene was carried out in a semi-batch minireactor using a commercially supported Ziegler– Natta (ZN) catalyst. The influence of variables including monomer partial pressure, external electron donor, reaction temperature and time on the particle morphology and size distribution was investigated. Generally, more uniform fragmentation and particle densities were obtained at lower reaction rates. Monomer partial pressure showed a significant role of particle size and its distribution, the higher the monomer partial pressure, the broader particle size distribution was obtained. Polymerization pressure had a significant role on the morphology of particles. Wider cracks and more porosity were resulted from the Polymerizations at higher pressures. Furthermore, a broader particle size distribution was obtained from the Polymerization at higher pressures. The particle size analysis revealed the monomer partial pressure as the most effective parameter on the distribution of particles. The SEM images showed that three different steps could be distinguished in the development of particle morphology within the particle, showing the initiation and development of cracks and appearance of fragments inside the particle.

This work presents an experimental study dealing with the deviations from the ideal flow models in the case of the flow of ε-caprolactam and, respectively, of the polymer melt, along an industrial unit for polyamide-6 synthesis. The flow pattern was determined by analyzing the mean residence time and dispersion criterion, which were obtained from radiotracer measurements. Different flow types were evidenced for different zones of the industrial Polymerization unit plug-flow with small mixing contribution in the reactor feeding pipe and in the prepolymerizer device and stirred flow with flow defects (stagnant zones and recirculation) for the Polymerization column. The analysis of the residence time distribution functions revealed different flow patterns according to different regions of the Polymerization column. We estimated the stagnant volume of each Polymerization zone by comparing the experimental mean residence time and corresponding nominal residence time, defined as the ratio between the total volume of the zone and the volumetric flow rate. The detection of some important flow anomalies occurring in the 3rd and 4th zones of the Polymerization column indicates the positions requiring an improvement of hydrodynamic regime. These experimental results were used and to ameliorate the operating regime of the ε-caprolactam Polymerization unit.

Cyanoacrylates have gained widespread attention and found applications across various industries due to their exceptional bonding capabilities. This study delves into the fundamental aspects of cyanoacrylate chemistry and Polymerization mechanisms to address the challenges associated with premature curing and enhance the understanding of the underlying processes. Cyanoacrylates, recognized for their exceptional adhesive properties, undergo rapid Polymerization catalyzed by minute amounts of moisture. The essence of the problem lies in the need to optimize the Polymerization process to prevent premature bonding and ensure controlled curing. The investigation involves a comprehensive analysis of cyanoacrylate's chemical makeup, and its adhesive potency. Notably, the study explores the inadvertent discovery of cyanoacrylates during World War II, underscoring their versatile applications and the need for a nuanced understanding of their reactivity. Findings reveal the intricacies of cyanoacrylate Polymerization, shedding light on the factors influencing the process, including temperature, humidity, and substrate composition.